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Improving Usability with a Website Index

Indexes are important information-finding tools that can enhance website usability. They offer easy scanning for finding known items, they provide entry points to content using the users’ own vocabulary and they provide access to concepts discussed, but not named, in the text. Perhaps most importantly, site indexes provide direct access to granular chunks of information without the need for traversing multiple links in a hierarchy.

What are indexes?
Before I explore how website indexes can improve usability, let’s start with background knowledge that will help show how they fit into the broader picture, especially since indexes have more to them than people often assume.Although great strides have been made with the technology, automatic classification tools come nowhere near the human brain in terms of accuracy in evaluating text.According to Nancy Mulvaney an index is “a structured sequence—resulting from a thorough and complete analysis of text—of synthesized access points to all the information contained in the text.”1

What are the important points about this definition? First, that the index is a sequence, that is, it has a known order of items. While most indexes are arranged alphabetically, other orders are possible, such as numerical (for a parts list index) or chronological (for a timeline). But the index isn’t just a list of entries, it is structured. In other words, the index shows relationships between various subjects, thus leading users to more specific or related topics that might meet their information needs more closely.

Most importantly for the construction of an index, a human has looked at and analyzed the text. Although great strides have been made with the technology, automatic classification tools come nowhere near the human brain in terms of accuracy in evaluating text. There is simply too much contextual meaning that texts carry, too much social and cultural knowledge that while not stated in the text, needs to be accounted for when creating the index. Certainly no computer can yet understand the actual meaning of all texts.

Mulvaney’s final point is that the index comprises access points to all the information contained in the text. An index contains all significant mentions of people, places, things and ideas. Important here is the idea of significance. An index should lead users to relevant material, to significant content chunks that provide useful information, rather than to passing mentions of words.

Thus, indexes are not concordances—lists of every occurrence of every word in a text. This is primary reason why indexes are much more valuable in certain cases that searches. Search results are often overwhelming or even useless; the fact that a word or phrase is mentioned in the text does not mean that the subject is discussed in the text. And it is the discussion that provides information for the user.

How do indexes increase usability?
Indexes, as flat lists of terms, are easily scannable. Users need only use their browser’s scroll bar to navigate through the entire index. (Large indexes often provide alphabetical anchor links at the top of the index, which take users quickly to the portion of the index they need to use.) There are no multiple levels to navigate, nor must users decide which branch of a hierarchy to click on, which often results in their missing information they are looking for or taking longer to find it. In fact, the easy scannability of the index on a single page is an important argument against having separate pages for letter of the alphabet, whenever possible.

Through the use of multiple access points or “see” references, indexes help translate the vocabulary of the users to that of a text. In this example, for instance:

cancer. See oncology

The index is telling the user that this site does have information on cancer, but that it uses the term “oncology” to represent this concept. And, if users click on the link, the index will bring them directly to the relevant information about that term.

“See also” references can lead users to additional or more specific information that might more closely meet their information needs. Every reference librarian knows that many users come to them with ill-formed queries. “See also” references assist users by helping them think about the information they are looking for.

training. See also online training; web-based training

Indexes are especially useful in “know-item finding,” those cases where users know specifically what they are looking for (or what information they saw previously and want to get back to). They simply find the term in the index and click on the link to go directly to the information. No need to drill down through multiple site levels or try to remember what path they took before.

Indexes can also serve an important function by leading users to concepts discussed but not specifically mentioned in the text. For example, a good indexer analyzing a paragraph that talks about Alpo and Purina Dog Chow might add an index entry for “pet nutrition.” Such intellectual analysis and synthesis adds significant value for users. Automated indexing tools fail at providing this kind of added value.

A site index acts as an important complement to the site map or table of contents. Where the latter look at the high-level (or top-down) organization of information on the site, indexes look at the bottom-up view, that is, at specific, granular information chunks.

When should site index be used?
Clearly, small sites have little need for indexes. Usually the navigation labels and page titles themselves will be enough for users to find the information they need (assuming that labels have been well thought out and provide an appropriate information scent).

For extremely large sites, with millions of pages, including everything in the index would be so time consuming and labor intensive as to be uneconomical. In addition, the resulting index would be almost impossible to scan. However, such sites can be improved and their usability increased by providing an index that directs users to the set of information that is most used or that most users need to do their jobs efficiently.

Most mid-sized sites, with hundreds or thousands of pages can benefit from the additional navigation that site indexes offer and can be indexed in a reasonable amount of time at a reasonable cost.

How are website indexes created?
Indexing, no matter what the material under consideration, consists of two steps. First, the content is analyzed to establish indexable concepts and then terms (or labels) for those concepts are created or selected. In website indexing, the URL for the page on which the information resides is captured and used to turn the index term into a hypertext link. For best results, a human mind needs to do the content analysis process.

There is software available, such as HTML Index, that helps automate the index preparation process by spidering a site and creating a preliminary version of an index using page titles and named anchors. The indexer then needs to massage those results to create a truly useful index.

Indexers can also create a site index using regular indexing software. CINDEX, MACREX and Sky Professional are the programs most used by professional indexers to assist with important, but time-consuming housekeeping tasks such as alphabetizing entries, checking spelling or verifying cross references. After the initial index entries have been created, they can then be copied or output (with embedded HTML coding) into a content management system’s index page template for later publishing to the website itself.

That process was the one I used to create the site index for PeopleSoft, Inc.’s website, which won an Australian Society of Indexers Web Index Award 2002–2004. Here, for example is the simple link code used to create the fourth line in the PeopleSoft site index illustrated below:

Special codes (available in most indexing programs) were used to “hide” the HTML coding so that the program alphabetized only the actual index labels themselves.

Having the site index use the conventions of back-of-book indexes, for example, indented subheads, makes it instantly recognizable for users. If they have any familiarity at all with using indexes, they will feel right at home with your site index. And that helps make for good usability.

Creating index labels
Label terms for indexes may be created by one of two different methods, depending on whether indexing is being carried out in a “closed” system or an “open” system.

In the former, nothing other than the text itself needs to be considered. The indexer derives index labels using “literary warrant” from the terminology used in the website itself and adjusts the labels as necessary for whatever reason.

Alternately, in an open system, the indexer selects terms from a previously created list of terms that exists separately from the text itself. These term lists may be authority files, simple lists of approved terms, or thesauri, which show relationships between terms (related terms, broader terms or narrower terms) that help the indexer select the most appropriate term to describe the specific text being analyzed. Open system indexing is used in cases where it is necessary to ensure consistency among multiple, related sites or to control vocabulary in a single large, complex site with multiple authors.

Who should create site indexes?
Whenever possible, a professional indexer should be hired. Such individuals are thoroughly experienced in analyzing content, accounting for user terminology and in creating an appropriate index structure.

The American Society of Indexers has an indexer locater on its website through which you can find indexers with experience in indexing web/HTML documents.

Corporate librarians often have training or experience in indexing and can also be important resources in identifying individuals with indexing skills.

Index maintenance
Once you have created a fabulous site index and have tested it to ensure that all its links work properly, you need to have an index maintenance policy in place. You will need to consider such things as: How often does the index get updated? Who decides when newly created information gets included. When does ROT (redundant, outdated or trivial information) get removed? Who is responsible for updating the index?

Keeping this important information access tool up to date will help ensure that your site’s users continue to find what they need when they need it.

Fred Leise, president of ContextualAnalysis, LLC, is an information architecture consultant providing services in the areas of content analysis and organization, user experience design, taxonomy and thesaurus creation, and website and back-of-book indexing.

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Fred Leise

Fred is a taxonomy design consultant and back-of-book indexer, with experience in information architecture and user experience research. He serves as senior taxonomist for K Street Partners.
He previous served as manager of the taxonomy team for the Online Business Unit of Sears Holdings Corporation. He is an indexing instructor for the University of California, Berkeley Online Extension Division and regularly presents sessions and workshops on taxonomy design and indexing.
He trained as an information architect at Argus Associates and has worked with such clients as Salesforce, IGT (international gaming company), Harpo, Inc., Disney, Abbott Laboratories, Accenture, LookSmart.com, and Hewlett-Packard. View all posts by Fred Leise

I realize that this article is dated, but I need to know if software exists that will permit us to use an index-term markup language that we created. We need it to crawl our site, find the coding, harvest terminology and index level of the term, grab the URL and return the info to a database where the terms can be aggregated for multiple references to the same term for multiple links.

Re: multiple indexes. Studies of multiple indexes in books (e.g. subject index, name index) seem to conclude that they are a bad idea – users often fail to make use of all the indexes or search for a term in the wrong index. I’ve never seen anything dealing with multiple indexes in websites. Multiple indexes would detract from the ‘scannability’ highlighted in the article.